A zap to the brain can improve language comprehension, according to a new study.
Researchers from the University of Pennsylvania School of Medicine found that transcranial direct current stimulation can improve a person's language processing skills by speeding up comprehension of meaningful word combinations.
"Integrating conceptual knowledge is one of the neural functions fundamental to human intelligence," said Amy Price, of the neuroscience department at the University of Pennsylvania School of Medicine and first author of the current study. "For example, when we read or listen to a sentence, we need to combine, or integrate, the meaning of the words to understand the full idea of the sentence. We perform this process effortlessly on a daily basis but it is quite a complex process and little is known about the brain regions that support this ability."
Recent MRI and magnetoencephalography studies have linked the left angular gyrus to semantic memory integration. Previous studies show that the angular gyrus is involved in language, number processing and spatial cognition, memory retrieval and attention.
Researchers in the latest study examined how the left angular gyrus affected semantic memory in 18 healthy adults. Participants underwent three different transcranial direct current stimulation sessions of either the left angular gyrus or the right angular gyrus, or sham stimulation.
"We sought to understand how and in what part of the brain semantic representations are integrated into more complex ideas" said Dr. Roy Hamilton, an assistant professor in the departments of Neurology and Physical Medicine & Rehabilitation of the University of Pennsylvania and senior author of the study.
Participants were asked to look at word pairs that were either meaningful like "plaid jacket" or non-meaningful like "fast blueberry." They were then asked to complete a letter task that served as a control for brain stimulation affects on vision and attention by looking at a string of letters like "vsbsl" "vsbql" and asked to say whether they matched.
Study results revealed that transcranial direct current stimulation resulted in significantly faster comprehension of meaningful relative to non-meaningful word pairs when compared to results from both control and right angular gyrus stimulation. Researchers noted that the finding was not replicated in the letter-string task, suggesting that that the results weren't linked to lower level visual processing, attention or motor control.
"Our findings extend our knowledge about the angular gyrus as a center wherein the brain constructs higher-level meaning from individual words during semantic comprehension and plays an important role in the fluent composition of meaning in language," Hamilton said. "They are also consistent with the broader claim that the angular gyrus is a cortical semantic hub."
The findings are published in the Journal of Neuroscience.
